The challenge to build a large symmetric multiprocessor (SMP) computer is many interconnections are required. These interconnections connect each CPU (central processing unit) with every other CPU over a short distance. This creates a three dimensional nest of interconnects; each of interconnects are required to be shorter than a maximum trace length dictated by electrical performance requirements.
One approach to connect all the CPUs together is to create a backplane with all the CPUs (generally the CPUs are configured on several CPU boards/cards) connect to a same side of this backplane. Due to the requirements of maximum trace length, the CPUs (or CPU boards/cards) have to be placed very close to each other. The overall number of CPUs included in the system is dictated by the maximum allowable trace length. That is because each additional CPU (or CPU board/card) added to the backplane connection also increases the trace length between CPUs.
Another approach in the prior art to meet the aforesaid requirements is to use orthogonal connectors that allow each CPU board to connect to another CPU board in a right angle fashion. Currently, such connectors of this type available include connectors of Molex I-Trac and Amphenol-TCS (Teradyne). Not only are these connectors more expensive than traditional backplane connectors, these connectors also created a difficult cooling problem. When boards are placed in an orthogonal fashion, it creates a crisscross airflow path that makes it very difficult to bring cooling air into the system and guide warm air away from the components.